Q-Chem provides a comprehensive ab initio quantum chemistry program, allowing scientists worldwide to solve computational problems quickly and accurately.
Joined January 2012
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8 Dec 2025
Q-Chem 6.4 is here! Upgrade for new spectroscopy features (such as CVS-XCIS our new-and-improved ΔSCF driver), iterative CC-in-DFT embedding, faster CC calculations, MR-SF-DFT, stochastic RI-CC2, NEO methods, and more: q-chem.com/explore/qc64/
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Jun 12
Q-Chem 7 includes many improvements to CC2:
* Large speedups for RI-CC2 ground state
* CC2 and RI-CC2 Dyson orbitals for EA, IP, EE-EA, and EE-IP
* RI-CC2 and sRI-CC2 oscillator strengths (read their paper: arxiv.org/html/2509.06460v1)
Pre-order Q-Chem 7! q-chem.com/purchase/
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Jun 10
Q-Chem 6 has introduced several new CC methods, including EOM-CCSDT for high accuracy for EE, SF, IP, EA, DIP and DEA, implemented by Summer At Q-Chem intern Manisha. Watch the webinar about this work: youtube.com/watch?v=590rAdAS…
Try Q-Chem today: q-chem.com/try/
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Jun 2
New in Q-Chem 7: CAP-DFT! From author Charlotte Titeca: "[CAP-DFT] enables fast and accurate evaluation of the energies and lifetimes of metastable molecular anions. ...Hybrid functionals deliver results that are competitive with EOM-CC theory." pubs.acs.org/doi/10.1021/acs…
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May 27
Q-Chem offers state-of-the-art tools for handling electron correlation, such as MP2 and CC methods; the Q-Chem 6 generation has included new correlated methods like EOM-CCSDT, BW-s2, TDDFT/TDA-SOC, and MRSF-TDDFT. Stay tuned as we highlight recent and upcoming features!
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May 25
Researchers recently probed the origins of homochirality in biological systems and found that electron spin may be the key. Their conclusions are supported by EOM-EA-CCSD and Breit-Pauli SOC calculations in Q-Chem. iopenshell.usc.edu/pubs/pdf/…
Try Q-Chem: q-chem.com/try/
ALT DNA molecule alongside a text citation for the paper linked in the main post.
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May 22
New in Q-Chem 7: Excited-state analysis based on Earth Mover's Distance (EMD)! This provides a new quantitative metric for characterizing charge-transfer in excitations. Read the paper from the developers: doi.org/10.1021/acs.jctc.3c0…
Pre-order Q-Chem 7: q-chem.com/purchase/
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May 20
Q-Chem's Δ-ALMO(MSDFT2) combines ΔSCF with ALMO to generate diabatic states, then uses MSDFT2 to obtain their couplings with charge-transfer states. Here, developers test Δ-ALMO(MSDFT2) on systems ranging from singlet fission to DNA repair: doi.org/10.1063/5.0035593
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May 18
New in Q-Chem 7: Excited-state analysis for MRSF-TDDFT, including natural orbitals (NOs), natural transition orbitals (NTOs), natural difference orbitals (NDOs), and related descriptors. Read the developers' recent preprint: doi.org/10.26434/chemrxiv.15… #compchem
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May 16
Practical application of Q-Chem's wave-function analysis: Developers use spin-orbit NTO analysis for TDDFT and SF-TDDFT (added in Q-Chem 6.1) to assess the character of different states, allowing them to properly compare spin-orbit coupling results. doi.org/10.1063/5.0130868
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May 15
Q-Chem 6.3 has new charge-transfer metrics for TDDFT, helping researchers identify orbitals most likely to participate in charge-transfer-to-solvent (CTTS) excitations, with applications to solution-phase chromophores. doi.org/10.1021/acs.jctc.1c0…
Try Q-Chem: q-chem.com/try/
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May 11
Q-Chem provides a wave-function analysis toolkit (libwfa) that enables visualization of excited states, automatic assignment of properties, and deeper insight into the underlying physics. QC6 has included several new additions, including CT metrics for TDDFT and Δ-ALMO(MSDFT2).
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May 8
The broken bond orbital (BBO) approach, introduced in QC 6.3, uses an EDA framework to assess key mechanisms at play during bond formation, helping researchers better understand the nature of chemical bonding. Watch the recent webinar here: q-chem.com/webinars/78/
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May 6
New in Q-Chem 7.0: EDA and OO-DFT OVOCV! Occupied-virtual orbitals for chemical valence (OVOCV) can be used to replace or complement NOCV analysis in EDA; it provides clearer identification of donor and acceptor orbitals than NOCV methods. doi.org/10.1021/acs.jpca.4c0… #compchem
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May 1
Force decomposition analysis (FDA) extends EDA to forces, allowing researchers to break force down into different physically-meaningful components. It provides information beyond EDA, including data that can be used to train physics-based #forcefields. pubs.acs.org/doi/10.1021/acs…
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Apr 29
Q-Chem's energy decomposition analysis (EDA) tools have seen many improvements in QC6, including POL and NOCV analysis and force decomposition analysis. We're excited to have new EDA features in our upcoming 7.0 release! Learn more about EDA in Q-Chem: manual.q-chem.com/latest/Ch1…
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Apr 25
In this recent collaborative preprint, researchers use experimental and theoretical techniques to investigate Norrish Type-I reactions. Q-Chem's OO-DFT is one technique they use to model spectra. arxiv.org/abs/2603.18339
Learn more about OO-DFT in Q-Chem: q-chem.com/webinars/68/
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Apr 23
It's still not too late to register for today's webinar! Join us at 11AM Pacific time to learn more from Juan E. Arias Martinez about his work creating an easier-to-use OO-DFT interface in Q-Chem, and how he's applied it in practical research applications.
Apr 21
Don't forget about our upcoming Q-Chem webinar from Juan E. Arias Martinez on his recent work creating a new OO-DFT (ΔSCF) interface in Q-Chem! He will also discuss how he has used the new interface to study donor-acceptor charge-transfer excitations. zoom.us/webinar/register/WN_…
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Apr 22
Vibrational circular dichroism (VCD) is a key technique for distinguishing between molecular enantiomers, which is essential in areas like drug discovery. Q-Chem 6.4 provides restricted and unrestricted ab initio predictions of VCD spectra.
Try today: q-chem.com/try/
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Apr 21
Don't forget about our upcoming Q-Chem webinar from Juan E. Arias Martinez on his recent work creating a new OO-DFT (ΔSCF) interface in Q-Chem! He will also discuss how he has used the new interface to study donor-acceptor charge-transfer excitations. zoom.us/webinar/register/WN_…
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Apr 17
Core-level spectra reveal a lot about valence virtual orbitals, especially for open-shell systems, but current methods often suffer from spin contamination. CVS-XCIS resolves the spin contamination issue, enabling accurate calculations for these systems. youtube.com/watch?v=PN-LyN2q…
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